Semitrailer supporting structure



Sept. 16, .1941. F. M. REID SEMITRAILER SUPPORTING STRUCTURE Filed May 5, i940 INVENT6R Eerici M Fez Z.

Patented Sept. 16, Q 1 941' 2,256,328 ssm'rannnn SUPBORTING'STRUCTURE Frederick M. Reid, Detroit, Mich., assignor to Fruehauf Trailer Company, Detroit, Mich, a

corporation of Michigan Application May a, 1940, Serial-No. 333,184

lClaim. (01. 254-86) i This invention relates. to supporting structures for semi-trailers and particularly to means for eliminating certain disadvantages thereof present, in conventional constructions when employed on relatively soft surfaces.

Objects of the invention include the provision of means associated with the retractable front from becoming imbedded to an undesired degree when contacting soft or relatively soft ground or road surfaces; the provision of means supplesupporting legs of semi-trailers to prevent them mentary to the usual wheels or rollers at the low-- er' ends of semi-trailer supporting legs for limiting the depth to which such rollers may be imbedded in soft supporting surfacesythe provision of a supporting leg structure for a semitrailer having wheels or rollers at the lower ends thereof together with planular supporting surfaces arranged in cooperating but non-interfering relationship with respect to said wheels or rollers for the purpose of supplementing the bearing area of the wheels on a supporting surface upon the wheels or rollers becoming imbedded therein beyond a predetermined amount;-

- and the provision of a. retractable supporting leg structure for the front end of a semi-trailer and having rollers or wheels at the lower end thereof, together with shoes arranged in flxed relation with respect to said leg structure and provided with a planular surface adapted to be arranged in approximately parallel relation to the surface of a road when said wheels or rollers arepo'sitioned in operative relationship with respect to the same and with said planular surface spaced vertically above the. lower edge of said rollers .by a relatively small but material distance.

trailer illustrating the forward end of the same as being supported in operative relationship upon the rear end of a tractor, the latter being shown in fragmentary, side'elevational view, and the front supporting leg for the semi-trailer being shown in operative relation with respect to the ground;

Fig. 2 is a plan viewv of the semi-trailer shown in Fig. 1;

Fig. .3 is a fragmentary, front elevational view of the supporting leg'structurefor the semitrailer shown in the-preceding views and taken looking in the direction of the arrows 3-3 of Fig. 1; and, I

Fig. 4 is a view similar to Fig. 3 but illustrating-a modified form of construction.

Supporting leg structures for the front ends of semi-trailers are provided in a number of different types. In some constructionsthe legs are pivoted at their upper ends to the frame of the semi-trailer and means are provided for swinging the free ends of the legs upwardly out of contact with the ground when the. front end of the semitrailer is supported by a tractor, and downwardly into contact with the ground. for supporting the front end of the semi-trailer when the tractor is withdrawn. Other constructions are provided with means for'reciprocating the lower portion}. 'of the leg structure vertically'to achieve the same purpose. Some of these leg structures are operated automatically by the connecting or disconnecting movement'of the tractor in'relationto the semi-trailer, some are operated by fiu id pressure means, and some are operated manually. The present invention is adaptable for use with any of the known typesof supporting leg structures but for the purpose of simplicity in description reference will be made only to that type thereof consisting of pivoted legs manually 'operable to operative or inoperative position, the description of the invention applied to this particular type of supporting structure making apparent to those skilled in the art how it can be similarly applied to other types of structures.

Regardless of the particular type of supporting leg structure employed for semi-trailers, such structures are universally provided with rollers at their lower ends for contact with the ground, road, or other supporting surface. Such rollers are provided primarily for the purpose of; permitting ease in movement of the semi-trailer when the frontend thereof is not supported by a tractor. Wheels contacting a hard surface theoretically have line contact with 'such surface and consequently any weight carried by the wheels exerts a high unit pressure upon the surface. Whcre the ground' or other supporting surface is hard or relatively hard the wheels of the supporting legs of a semi-trailer are impressed into the supporting surface to such slight extent as not to materially interfere with the free rolling of the wheels upon the surface. However,

if the supporting surface is soft, and particularly where the semi-trailer is heavily loaded, the

wheels at times become imbedded in the supporting surface to such an extent as not only to make it extremely difficult to move the semi-trailer without supporting the front end thereof on a tractor or the like, but oftentimes permits the front end of the semi-trailer to drop so lowas to render it impossible to get the rear end of a tractor under it for the purpose of coupling the two together. This is not an uncommon occurrence where thesemi-trailers are in a loading yard or the like of unpaved character and where the yard has been softened by thawing, rains, or the like.

It is the purpose of the present invention to provide means associated with such supporting legs to prevent the wheels or rollers thereof from becoming imbedded in the supporting surfacetherefor to an undesirable extent and to accomplish this result in a simple and economical manner.

Referring now to the accompanying drawing the numeral I indicates generally the frame structure of a semi-trailer and upon which a body of any suitable type or construction may be mounted in a conventional manner. The rear end of the frame I0 is supported by means of a pair of conventional wheels l2 suitably mounted .upon a conventional axle structure It connected to the frame ID by means of springs Hi. When in operation the forward end of the frame I8 is supported upon the rear end of a tractor indicated generally at l8. For this purpose the rear end of the tractor I6 is provided with a conventional fifth wheel structure 28 and the forward end of the frame i8 is provided with a downwardly extending kingpin 22 which is received by and secured in the fifth wheel 20 for the purpose of supporting the forward end of the semi-trailer during travel and for the purpose of providing a pivotable draft connection between the tractor and trailer.

In order to provide a support for the forward end of the semi-trailer when not supported by the tractor l8, a supporting leg structure is provided adjacent the. forward end" of the semi trailer which, for the purpose of illustration, is constructed as follows. At opposite sides of the frame III a bracket 24 is fixed to the outer lower faces of the opposite frame side members. Pivotall secured to each of the brackets 24 as by means of a pin 26 is a supporting leg 28. This supporting leg may, if desired, be .made in two or more longitudinally adjustable sections se-' of the axle 38 project through the bifurcated lower ends of the corresponding legs 28, and each rotatably receives thereon within the bifurcation a supporting wheel or roller 32. Cross-braces 'such as 34 are preferably provided between the legs 28 for the purpose of bracing them transversely of the semi-trailer.

. In order to move the legs 28 and rollers 32 from a position in which the legs and rollers support the forward end of the semi-trailer from the shaft or :xle 30. The struts 36, as shown,

. ment on a slide structure 48 fixed to the frame i0 centrally thereof and extending longitudinally thereof between a suitable pair of cross-members of the frame l8.

The block 38 is provided with an upwardly ex tending nut portion 42 within which is threadably received a longitudinally extending screw 44, suitablysuppirted by the frame for rotatable movement but fixed against relative axial movement. As best illustrated in Fig. 2 the forward end of the screw 44 extends into and is carried by a gear box 46 and within the gear box 46 has fixed thereto a bevel gear 48 which lies in mesh with another bevel gear 58 secured to a shaft 52 which extends out through the gearbox l6 and through the side of the frame l0 where its outer end is supported in a bracket 54 fixed to the frame. A crank 56 is provided on the outer endof the shaft 52.

It will be appreciated that by turning the crank 56, the shaft 52 and gear will be rotated, thereby causing rotation of the gear 48 and screw 34. Rotation of the screw 44 will cause the nut 42 and consequently the block 38 to move longitudinally of the slide or guide," depending upon the direction of rotation of the crank 56, and movement of the block 38 longitudinally of the vehicle will cause a corresponding longitudinal movement of the upper end of the struts 36 and consequent pivotal movement of thelegs 28 about the pivot pins 26 to raise or lower the wheels 32. It will be understood that when the front end of the semi-trailer is not supported by a tractor, such as l8, the legs 28 are moved to their operative position illustrated in Figs. 1 and 2 with the wheels 32 in contact with the ground, and that after'a tractor'such as It has backed under the front end of the semi-trailer and has been locked thereto, the crank 56 will be operated to move the block 38 rearwardly and swing the legs 28 in a counterclockwise direction of rotation as viewed in Fig. 1 about the pivot pins 26 so as to raise the wheels 32 upwardly out of contact with the ground, such wheels being returned into contacting relationship with the ground prior to uncoupling of the tractor from the front end of the semi-trailer. y

In accordance with the present invention in order to prevent the wheels 32 from being buried I in the supporting surface when the supporting surface is unduly soft-and/or when the semitractor is heavily loaded, 1 provide supplementary 2 bearing surfaces in association with each of the wheels 32 and symmetrically arranged with respeot thereto, which bearing surfaces become op-' erative only after the wheels 32 have become imbedded a predetermined amount in such road or other supporting surface.

In the particular construction illustrated in their down or operative position. .The ends of the shoes are preferably upwardly turned or curved as best illustrated in Fig. 1. Each shoe 60 is preferably arranged in relatively close Proximity with its corresponding wheel 32 but sufficiently spaced therefrom as to be out 'of interfering relation with respect thereto. Its lower face is preferably positioned in a plane sufficiently vertically spaced above the lower'face of the corresponding wheel 32 that it will come into contact-with the supporting road or other surface only after the corresponding wheel-32 has begun to imbed itself into such surface to an undesirable extent. Preferably the lower face of the shoes 60 are spaced an inch to an inch-and a half above the lower face of the wheel 32, but it will be appreciated that this dimension may be varied one way or another depending upon conditions or the desires of the individual designer. a

In any event the lower face of each shoe ill is of a material area as compared to the projected area of the peripheral surface of the corresponding wheel 32 so that when the corresponding wheel 32 embeds itself into a supporting surface,

ference with the normal action of the wheels 32 will result.- It will thus be appreciated that the shoes 63 are auxiliary to-the wheels 32 and come into action only under those conditions where side of each supporting leg in order to increase the available bearing area between the supporting leg structure and the ground. Such construction is illustrated in Fig. 4. Where such construction is employed, the leg 28 previously described may be modified to provide a shoe structure by extending the leg 28" downwardly below the shaft or axle 30 and forming on the lower end thereof a shoe 60", corresponding inposition, function and results to the shoes 60 previously described.

The shoe 30" in this case is, of course, located midway between the wheels 32 as illustrated in Fig. 4, and, therefore, symmetrical with respect thereto.

From the above description it will be appreciated that the present invention provides a simple and effective means for limiting the amount which the-usual wheels or rollers of the supporting leg structure of a semi-trailer may embed themselves in a supporting surface where the supporting surface is relatively soft, the load on the trailer is relatively large, or both these factors occur simultaneously, and that by limiting .the

embedding of the wheels in the supporting surface a real and material advantage is gained.

Formal changes may be made in the specific embodiments of the invention described without departing from. the spirit or substance of the broad invention, the scope of which is commensurate with the, appended .claim.

What I claim is: y

In a semi-trailer, in combination, a pair of retractable leg members, a shaft interconnecting corresponding ends .of said members, a wheel structure carried by said shaft adjacent each of said members, each of said members having rigidly fixed thereto downwardextensions having relatively fiat shoe means of material area arranged in a plane approximately normal to the. length of' said members, each said flat shoe means being symmetrically positioned with respect to the associated wheel structure, and being positioned intermediate said shaft and the peripheries of the wheels whereby to 'provide an auxiliary ground engaging surface adapted to support the semi-trailer at a fixed height in the event that the wheels sink into a soft supporting surface,

means for raising and lowering that end of said members carrying said wheels, and means for operativeiy connecting the opposite end of said members tosaid trailer. FREDERICK M. REID. 

